June 18, 2003 -- Genetic abnormalities may explain why some women with endometriosis suffer from infertility. New research shows that women with endometriosis-related infertility lack a certain enzyme in their uterus that allows the embryo to attach the uterine wall, which establishes a normal pregnancy.
Researchers say the finding could lead to new screening tests for the condition as well as treatments for endometriosis and the infertility often caused by it.
"The causes of endometriosis and of the infertility that's associated with it have eluded scientists for many years," says Duane Alexander, MD, director of the National Institute of Child Health and Human Development (NICHD, which partially funded the research), in a news release. "This study provides a better understanding of this disease, and may lead to new therapies to treat women who have the disorder."
Endometriosis affects 10%-15% of women of reproductive age and occurs when endometrial tissue that normally lines the inside of the uterus spreads to other organs, such as the fallopian tubes, intestines, and ovaries. The severity of the condition varies greatly among women and may cause no symptoms at all, but it can also lead to severe pelvic pain and infertility.
Discovery Adds Evidence to Endometriosis-Infertility Link
Researchers say the discovery builds on previous research that found a molecule known as L-selectin needs to be present on the uterine wall for an embryo to attach itself and allow a pregnancy to begin.
In this study, researchers found that at the moment in a woman's menstrual cycle when the uterus is most receptive to embryo implantation (days 20-24 of a 28-day cycle), women with endometriosis-related infertility lack an enzyme that holds L-selectin in place on the wall of the uterus, making it impossible for the embryo to attach itself.
Researcher Linda Giudice, MD, PhD, of Stanford University, and colleagues also found that certain genes also appear to be malfunctioning in the endometrial tissue of women with endometriosis, based on samples they collected from 15 non-pregnant women, eight with endometriosis and seven without.
The findings, published in the July issue of Endocrinology, may also lead to new, noninvasive ways to screen women for endometriosis. Currently, diagnosis of the condition is usually confirmed through a surgical procedure called a laparoscopy or laparotomy, to remove tissue samples from the abdomen.
But if further studies confirm these results, researchers say new treatments and a screening test that detects the abnormal genetic activity associated with endometriosis may one day be developed.
"This now offers an opportunity to create drugs to correct this error in gene expression, and therefore a treatment for endometriosis-related infertility," says Giudice in a news release.